A steering wheel for automotive vehicles comprises the usual rim, which can be of round cross-section, connected to a hub by spokes. In a bowl-shaped wheel of the type with which the present invention is concerned, the hub is connected to a bowl from which the spokes extend.
Deformable members are used to increase the passive safety in motor vehicles. When the motor vehicle is sharply decelerated due to an accident, the deformation member is intended to prevent an impact of the head of the driver on the upper portion of the steering wheel rim or on steering wheel spokes when the maximum load of the safety belt applied by the driver has been exceeded.
When a driver who has not used a safety belt is involved in a collision at low or medium speed, such deformable members have been found to decrease the risk of an injury from the impact of the body of the driver on the steering wheel.
Known deformable members have included metallic deformable pots or bowls connected between the steering wheel and steering column (German Federal Republic Pat. No. 947,048), or deformable tubular elements of metal, which have diamond-shaped apertures (German Patent Publication-Auslegeschrift-No. 19 12 528).
A deformable member which has a smooth surface and occupies a substantial part of the cross-section of the steering wheel and consists entirely of an inelastic, homogeneous hard foam of polyurethane or the like, only capable of plastic deformation, may be arranged within the rim of the steering wheel and secured to the steering wheel hub (German Federal Republic Pat. No. 23 12 843).
It is also known to cover the rim and spokes of the steering wheel and the periphery of the hub of the steering wheel with soft elastic synthetic-resin material in order to improve the passive safety and to improve the hand grip and the appearance. A deformable member consisting of the same synthetic-resin material may be provided on the rim of the steering wheel. Such elements are commonly known as wheel covers and can be applied in a variety of ways.
Particularly in zones containing a large amount of foam, such synthetic-resin foams have an inadequate inherent strength. For this reason, German Utility Model No. 75 30 843 teaches the use of reinforcing members, which are embedded in the plastic foam and secured, e.g., to the spokes of the steering wheel. Another disadvantage of conventional plastic foams used for this purpose is that they are capable only of elastic deformation.